An example of the background art in this technical field is the technique disclosed in JP-A-H7 (1995)-208766. According to this technique, in a room of a datacenter which must be air-conditioned, the floor is a free access floor entirely covered by rectangular units of a prescribed size through which air cannot get in and out. The free access floor enables an air conditioning apparatus to supply cooling air for cooling IT equipment in the datacenter to the underfloor space of the free access floor. One or more than one of the rectangular units constituting the underfloor space is (are) replaced by a unit (units) with an opening so that cooling air is supplied to the room through the unit(s) with an opening.
This system may be used not only in a datacenter but also in a clean room which must be always ventilated and air-conditioned. Alternatively a ventilation space for supply air and exhaust air which is constituted by rectangular units and freely accessible may be provided on a ceiling or wall surface.
The above system, in which the ventilation space is constituted by rectangular units and ventilation is done through a unit with an opening, has a feature that the location of the opening can be adjusted according to the destination of ventilation air or the object which takes in the air for efficient air ventilation even after installation of the system.
Furthermore, JP-A-H7 (1995)-333015 describes a device for measuring the air-conditioned state of a freely accessible underfloor space which includes various sensors and measuring instruments mounted on the back surface of a free access floor member or a plate of the same size and made of almost the same material, in which these sensors and instruments are capable of measuring at least the flow direction, flow velocity, temperature, and humidity to measure an air-conditioned state and are integrated into a unit. According to this measuring device, an ordinary free access floor plate can be replaced by this plate so that the air-conditioned state under the free access floor can be measured for a desired time period.
Furthermore, JP-A-2008-121911 describes a measuring system which includes a measuring unit with a wireless transmitter, as a measuring device to measure the air-conditioned state under a free access floor easily. According to this system, at least three wireless receivers are provided in places and the location of the measuring unit is detected according to the intensities of signals received by the receivers.
In a datacenter, the cooling air generated by an air conditioning apparatus (hereinafter referred to as an air conditioner) is supplied to the space under the floor, the space above the ceiling or the space behind the wall. The supplied cooling air cools the equipment which generates heat, such as a server, storage and network (hereinafter referred to as equipment) and the room.
In a room as a datacenter like this, the floor, ceiling or wall is constituted by rectangular units. One or more than one of these rectangular units can be replaced by a unit (units) with an opening. As a consequence of such replacement, cooling air can be taken in or out through the newly installed unit(s) and the location of the opening can be changed according to the destination of ventilation air or the object which takes in the air so that air ventilation can be done efficiently.
In that case, it is necessary to accurately measure, at several points, the flow rate of cooling air supplied through the unit(s) with an opening to the room where the equipment is installed. A possible approach to measuring the air flow rate is to bring an air flow rate measuring device close to the opening and measure the air flow rate directly. This approach has a problem that it may be impossible to make a measurement accurately because the air flow rate measuring device may block the opening.
In the measuring device described in JP-A-H7 (1995)-333015, the measuring device is accessed through a unit with an opening and the opening pressure drop during measurement is different from that during normal operation, so the measurement of the air flow rate in a situation that the measuring device is not installed cannot be obtained.
Furthermore, the layout of the room may be changed at any time and the optimum location of a rectangular unit with an opening varies depending on the layout of the room. Therefore, when a wireless transmitter is provided as in the measuring device described in JP-A-2008-121911, the place where a measurement has been made can be identified and it is easy to cope with change in the layout or change in the location of the measuring device.
However, the measuring device described in JP-A-H7 (1995)-333015 and the measuring device described in JP-A-2008-121911 are both designed to measure the air flow under the floor and in most related techniques, the air flow rate measuring device is fixed in a prescribed position of a free access floor member without an opening. These related techniques have a problem that it is impossible to measure the air flow rates in all openings by using a small number of measuring devices and changing their locations as necessary.
An object of the present invention is to provide a measuring device of air flow rate for an air conditioning system which accurately measures the flow rate of cooling air blowing out of the openings of some rectangular units and in which the locations of the openings can be changed according to the location of the equipment.